INTRODUCTION

Obesity alters lung function, can cause symptoms suggesting asthma, and may worsen preexisting asthma. The precise mechanisms on how obesity leads to or worsens asthma are not well elucidated. A combination of mechanical factors, adipose-released inflammatory mediators, and immune system activation appears likely responsible for the “obese-asthma” phenotype.

In this chapter, we discuss the evidence linking asthma to obesity, review the proposed mechanisms, and discuss the clinical care of obese individuals with asthma (see Box 7-1 for key clinical points).

LINKING ASTHMA AND OBESITY

Asthma prevalence has increased in parallel with obesity.1,2 Of US adults, 8% have asthma—an increase from the 1980 value of 3.1%.2 In the bariatric surgery population with body mass index (BMI) greater than 60 kg/m2, the asthma prevalence is estimated to be 33%.3

Obesity is defined as BMI greater than 30 kg/m2. While simple to calculate and commonly used, BMI is not the best measure of assessing body fat influence on respiratory diseases. BMI does not capture fat distribution patterns or assess metabolically active adipose. The android pattern (abdominal fat ...